function FindExtensionByClass(AClass: TScCertificateExtensionClass): TScCertificateExtension;
Description
Call FindExtensionByClass to determine if a specified extension class is referenced in the Extensions list. AClass is the class of the object for which to search. If FindExtensionByClass finds an item with a matching class, it returns the TScCertificateExtension object for the specified item. Otherwise it returns nil.